# static method一般用于工具类
class Calculator:
    @staticmethod
    def add(x, y):
        return x + y

    @staticmethod
    def sub(x, y):
        return x - y

    @staticmethod
    def mul(x, y):
        return x * y

    @staticmethod
    def div(x, y):
        return x / y


print(Calculator.add(1, 2))
print(Calculator.sub(1, 2))
print(Calculator.mul(2, 7))
print(Calculator.div(1, 3))